Research and development of non-aqueous electrolyte batteries in which charging and discharging are performed by transfer of lithium ion between a negative electrode and a positive electrode have been advanced actively as high-energy density batteries.
Various properties are desired for a non-aqueous electrolyte battery depending on the application thereof. For example, use at a discharge of about 3 C is estimated for use in power sources of digital cameras, and use at a discharge of about 10 C or more is estimated for use in hybrid battery automobiles and the like. Therefore, high current property is specifically desired for non-aqueous electrolyte batteries for use in these applications.
Currently, non-aqueous electrolyte batteries using a lithium-transition metal composite oxide as a positive electrode active material and a carbonaceous matter as a negative electrode active material are commercialized. As a transition metal for a lithium-transition metal composite oxide, Co, Mn and Ni are generally used.
In recent years, there is a fear that the safety of non-aqueous electrolyte batteries is decreased by the progress in increasing of an output, increasing of an energy density and increasing of a capacity.
For safety of a non-aqueous electrolyte, over-charge/over-discharge can be prevented by an outer circuit (protection circuit). On the other hand, an internal short circuit that is caused by, for example, incorporation of a conductive foreign substance in production steps cannot be prevented by an outer circuit (protection circuit). Therefore, it is necessary to address internal short circuiting by a battery itself.